Conventional antennas, such as dipoles, slots and patches that receive an electric field or magnetic field of an incident signal and convert it to an output signal must either protrude from the surface to which they are mounted or require a cavity in the surface behind them. Protruding antennas on aircraft increase drag and present anti-icing and other challenges. Antenna cavities on aircraft also add weight (reducing aircraft range/payloads), take up valuable space, result in holes through structural skins of the aircraft that are subject to lightning and fluid penetration, and are costly to integrate into the structure of the aircraft.